<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
        html {
            font-size: 1vw;
        }
        .box {
            width: 50rem;
            height: 50rem;
            background-color: pink;
        }
        .box2 {
            width: 50vw;
            height: 50vw;
            background-color: green;
        }
    </style>
</head>
<body>
    <div class="box"></div>
    <div class="box2"></div>
</body>
</html>